Sadly, it is still not working too well with Objective-C, which is currently my main language (1).
Luckily, unofficial VIM plugins for XCode like XVim (2) or VIEmu (3) are getting better and better, so at least I can use vim bindings for objective-c now, too. Nevertheless, good clang support in Vim would still be great, so that I could tap into the huge amount of vim plugins during objc development.
[1] https://github.com/Valloric/YouCompleteMe/issues/84
[2] https://github.com/JugglerShu/XVim
[3] http://www.viemu.com/